1 GNU Emacs Terms and Conventions

If you’re an experienced Emacs user, you can skip the following
conventions and definition of terms and go directly to the next
section (see Getting Started).

In general, functions in this text refer to Emacs Lisp functions
that one would call from within Emacs Lisp programs (for example,
(mh-inc-folder)). On the other hand, commands are those
things that are run by the user, such as i or M-x
mh-inc-folder. Programs outside of Emacs are specifically called MH
commands, shell commands, or Unix commands.

The conventions for key names are as follows:

C-x

Hold down the CTRL (Control) key and press the x key.

M-x

Hold down the META or ALT key and press the x key.

Since some keyboards don’t have a META key, you can generate
M-x, for example, by pressing ESC (Escape),
releasing it, and then pressing the x key.

RET

Press the RETURN or ENTER key. This is normally used to
complete a command.

A prefix argument allows you to pass an argument to any Emacs
function. To pass an argument, type C-u before the Emacs command
or keystroke. Numeric arguments can be passed as well. For example, to
insert five f’s, use C-u 5 f. There is a default of four when
using C-u, and you can use multiple prefix arguments to provide
arguments of powers of four. To continue our example, you could insert
four f’s with C-u f, 16 f’s with C-u C-u f, 64 f’s with
C-u C-u C-u f, and so on. Numeric and valueless negative
arguments can also be inserted with the META key. Examples
include M-5 to specify an argument of 5, or M-- which
specifies a negative argument with no particular value.

NOTE

The prefix C-u or M- is not necessary in MH-E’s MH-Folder
mode (see Reading Mail Tour). In this mode, simply enter the
numerical argument before entering the command.

Emacs uses variables to hold values. These can be changed via
calls to the function setq in ~/.emacs.

Variables in MH-E that are normally modified by the user are called
options and are modified through the customize functions (such
as M-x customize-option or M-x customize-group).
See section
Easy Customization in The GNU Emacs Manual.
See Options.

You can specify various styles for displaying text using faces.
MH-E provides a set of faces that you can use to personalize the look
of your MH-E buffers. Use the command M-x customize-face to do
this.
See section
Face Customization in The GNU Emacs Manual.

Commands often offer hooks which enable you to extend or modify
the way a command works.
See section
Hooks in The GNU Emacs Manual
for a description about normal hooks and abnormal hooks.
MH-E uses normal hooks in nearly all cases, so you can assume that we
are talking about normal hooks unless we explicitly mention that a
hook is abnormal. We also follow the conventions described in that
section: the name of the abnormal hooks end in -functions and all
the rest of the MH-E hooks end in -hook. You can add hooks with
either customize-option or add-hook.

There are several other terms that are used in Emacs that you should
know. The point is where the cursor currently is. You can save
your current place in the file by setting a mark. This operation
is useful in several ways. The mark can be later used when defining a
region, which is the text between the point and mark. Many
commands operate on regions, such as those for deleting text or
filling paragraphs. A mark can be set with C-@ (or
C-SPC).

The minibuffer is the bottom line of the Emacs window, where all
prompting and multiple-character input is directed. You can use
completion to enter values such as folders. Completion means
that Emacs fills in text for you when you type SPC or TAB.
A second SPC or TAB will list all possibilities at that
point.
See the section
Completion in The GNU Emacs Manual.
Note that SPC cannot be used for completing filenames and
folders.

The minibuffer is also where you enter Emacs function names after
typing M-x. For example, in the preface, I mentioned that you
could obtain help with C-h t (help-with-tutorial). What
this means is that you can get a tutorial by typing either C-h t
or M-x help-with-tutorial. In the latter case, you are prompted
for ‘help-with-tutorial’ in the minibuffer after typing
M-x.

The ‘~’ notation in filenames represents your home directory.
This notation is used by many shells including bash,
tcsh, and csh. It is analogous to the environment
variable ‘$HOME’. For example, ~/.emacs can be written
$HOME/.emacs or using the absolute path as in
/home/wohler/.emacs instead.

In case of trouble: Emacs can be interrupted at any time with
C-g. For example, if you’ve started a command that requests that
you enter something in the minibuffer, but then you change your mind,
type C-g and you’ll be back where you started. If you want to
exit Emacs entirely, use C-x C-c.